Field of the Invention
The present invention is in the field of processes for the generation of thin inorganic films on substrates, in particular atomic layer deposition processes.
With the ongoing miniaturization, e.g. in the semiconductor industry, the need for thin inorganic films on substrates increases while the requirements of the quality of such films become stricter. Thin inorganic films serve different purposes such as barrier layers, dielectrica, or separation of fine structures. Several methods for the generation of thin inorganic films are known. One of them is the deposition of film forming compounds from the gaseous state on a substrate. In order to bring metal or semimetal atoms into the gaseous state at moderate temperatures, it is necessary to provide volatile precursors, e.g. by complexation the metals or semimetals with suitable ligands. These ligands need to be removed after deposition of the complexed metals or semimetals onto the substrate.
Description of Related Art
US 2009/0 004 385 A1 discloses N-heterocyclic carbene copper precursors for deposition processes.
T. Schaub et al. disclose in Organometallics volume 25 (2006) page 4196-4206 the preparation of N-heterocylic carbene nickel complexes.
It was an object of the present invention to provide a process for the generation of inorganic films of high quality and reproducibility on solid substrates under economically feasible conditions. It was desired that this process can be performed with as little decomposition of the precursor comprising the metal as possible before it is in contact with the solid substrate. At the same time it was desired to provide a process in which the precursor is easily decomposed after deposited on a solid substrate. It was also aimed at providing a process using metal precursors which can easily be modified and still remain stable in order to fit the precursor's properties to the particular needs.